Ray Stephenson : Sedum rosulatobulbosum Koidzumi (1938) & Sedum bulbiferum Makino (1891)
Common names : Korai-ko-mochi-mannengusa; Ko-mochi-mannengusa.
Sedum bulbiferum has been included with S. alfredi and S. lineare in the past, but together with S. rosulatobulbosum it is unique in disintegrating and casting a multitude of adventitious buds or bulbils to the wind. Uhl and Moran do not differentiate between these two species for cytologically as well as vegetatively they have much in common. Dwellers of heavily shaded valleys in damp places, even on rocks in the middle of mountain rivulets, these oddities need special cultivation.
Stems rise to as much as 20 cm (8 in) high before flowering, producing copious quantities of bulbils, and then collapsing. In my experience, Sedum rosulatobulbosum is the most robust species with large adventitious bulbils, consisting of rosettes of almost-round leaves more than 1 cm (0,4 in) across. In addition, the species tends to be perennial with the main plant regenerating in spring.
Sedum bulbiferum is much smaller, with narrower leaves and tiny bulbils consisting of only a couple of pairs of opposite-decussate leaves. It tends to be annual or biennial. Makino says that in the wild all parent plants perish and that together these stonecrops are the most common in Japan. He says that only sterile seed is produced.